1. Field of the Invention
The present invention relates to a device and method for detecting a zero crossing and a voltage amplitude from a single pulse signal and, more particularly, to a device and method for detecting a zero crossing and a voltage amplitude of a commercial power source voltage inputted to an electronic device, from a single pulse signal.
2. Description of the Related Art
In the related art, individual circuits are provided to separately detect a zero crossing and a voltage amplitude. For example, a device for detecting a zero crossing and a voltage amplitude of a commercial power source voltage inputted to a product including an instantaneous water heating module such as a water purifier or a bidet will now be described with reference to FIG. 1.
FIG. 1 illustrates the configuration of the related art zero crossing detector for detecting a zero crossing of a commercial power source voltage. As shown in FIG. 1, when a phase voltage 1 of the commercial power source voltage is inputted, a comparator 2 outputs a high level voltage if the phase voltage 1 is larger than 0, and outputs a low level voltage if the phase voltage 1 is smaller than 0, to thus output a square wave voltage 3. A phase detector 4 detects the phase of the square wave voltage 3 to detect a zero crossing.
FIG. 2 is a circuit diagram of the related art circuit for detecting the commercial power source voltage. As shown in FIG. 2, as an electric potential VDD of a high electric potential side is supplied to a connection point 11, likewise, an electric potential VEE of a low electric potential side is supplied to a connection point 12, a resistor 14 is connected between the connection point 12 and another connection point 13, and a bias voltage generating circuit 15, a reference voltage generating circuit 16, a voltage dividing circuit 17, a voltage comparator 18, and a current path circuit 19 are sequentially connected between the connection point 11 and the connection point 13.
The bias voltage generating circuit 15 generates a certain DC bias voltage VB from a potential difference between the potential VDD at the connection point 11 and the potential VSS at the connection point 13. The DC bias voltage VB is set as a value with which a MOS transistor, which has a gate to which the DC bias voltage VB is supplied, operates in a weak inversion region. The DC bias voltage VB generated by the bias voltage generating circuit 15 is supplied to both the reference voltage generating circuit 16 and the voltage comparator 18.
The voltage comparator 18 compares a supplied reference voltage V1 and a divided voltage V2, and outputs an output voltage V3 according to the comparison result to the current path circuit 19. The current path circuit 19 supplies a current according to the output voltage V3 from the comparator 18 to between the current connection points 12 and 13, to generate a voltage drop at the resistor 14 to thus make an output voltage VOUT adjusted uniformly.
In this manner, in the related art, the zero crossing detector and the voltage detection circuit are separately installed to detect the zero crossing and the voltage amplitude of the commercial power source voltage inputted to an electronic device. Thus, the number of parts used for the products increases, leading to an increase in the production unit cost, so not only do the product supply costs increase but also spending appetite of consumers who want low-cost products cannot be satisfied.